Western lowland gorillas come from the dense forests of western central Africa. Over the past 25 years, their populations have fallen by over 60%.

Zoo curator Julie Mansell said: "Gorillas are facing the real and severe risk of extinction in their native habitat.

"The all too familiar problem of habitat loss and the gruesome yet growing bushmeat trade are the main reasons for this iconic species' decline.

"Not only are the young targeted for the pet trade, but adults are also killed for bushmeat and trophy hunting.

"In this instance, their young are taken and sold as pets, but they die of starvation or disease within days, and this could easily have been Gugas' fate."

Gugas, a silverback gorilla, was born in the wild and had an unfortunate start to life when his parents were killed, probably for bushmeat.

The young gorilla was then acquired by a Portuguese circus and became very ill.

He was abandoned at the gates of Lisbon Zoo before being moved to Stuttgart Zoo to live in a nursery group for orphaned gorillas.

He arrived at Belfast Zoo in 1998.

In 2012, with no sign of any pregnancies, the zoo tested Gugas' fertility and the results were not promising. In fact, there were doubts that he would father any young.

But the gorilla has defied the odds, going on to father three infants since 2013, including new arrival Olivia.

The thriving family join fellow gorillas Delilah, Kwanza and Kamili and infants Baako and Kibibi at the zoo.

Ms Mansell said: "Our gorillas are firm visitor favourites and people definitely have an affinity for the apes, possibly as they are our closest relatives.

"However, without major conservation efforts, the reality is that apes could be wiped out within the next few decades and within our own lifetimes, showing the fragility and magnitude of the situation."

As well as taking part in a European and collaborative breeding programme, the zoo provides support to African projects such as the cross river gorilla project run by the Wildlife Conservation Society Nigeria.